I've heard of this idea before. As I understood it the concept is to mimic the smell of a cell which is just about to be capped. Presumably the trap formed could be placed at the ends of the brood chamber or the floor.
Good luck to them if they can get it to work.
Perhaps they can then have a go at something for SHB?
Ross Conrad uses mite traps. He uses a standard frame covered with thin board and tiny slits. He then puts methyl palmitate (drone brood pheremone) in the bottom to attract the varroa.